Nearly half a century ago, psychiatrist John Bowlby proposed that the instinctual behavioral system that underpins an infant's attachment to its mother is accompanied by "internal working models" of the social world - models based on the infant's own experience with her caregiver. These mental models were thought to mediate, in part, the ability of an infant to use her caregiver as a buffer against the stresses of life, as well as the later development of important self-regulatory and social skills. Hundreds of studies now testify to the impact of caregiver behavior on infant behavior and development: Infants who most easily seek and accept support from their parent are considered secure in their attachments and are more likely to have received sensitive and responsive caregiving than insecure infants. Insecurely attached infants are at higher risk for the later development of both externalizing behavior problems such as conduct disorders and internalizing behavior problems such as depression and anxiety. The mental models of older children have been shown to predict many of the same developmental sequelae as do the more behavioral measures. Yet no study has ever directly assessed internal working models in infancy. The specific aim of the present proposal is to use established visual habituation methods to examine the impact of infants'experiences with their caregivers on their ability to represent and process abstract social relations. Two exploratory studies will be conducted with 12-month-olds. The first study will examine infants'expectations of caregiver responses to bids for attention. The second study will explore infants'expectations of infant responses to caregiver return. Performance on both studies will be compared to infants'attachment status as measured in the Strange Situation. The long-term goals are to examine (1) the interrelationships between these early cognitive representations and other emerging abilities in infancy, for instance how individual differences in goal- attribution or emotion recognition might interact with infants'interpretation of caregiver behavior, and (2) the relationship between early mental representations and long-term developmental adjustment, thereby suggesting new avenues for prevention and treatment of attachment-related maladjustment. Infants with poor attachments to their caregivers are at risk of later mental health problems such as anxiety, depression, oppositional defiant disorder or conduct disorder. This research uses established methods from the field of infant cognition to examine whether infants'understanding of social interactions is influenced by their experiences with their own caregivers. Such a finding would open new avenues for the prevention and treatment of attachment-related maladjustment in childhood.